The use of rendered animal products in aquaculture diets

Geoff L. Allan, N.S.W. Department of Primary Industries. Port Stephens Fisheries Centre, Nelson Bay, Australia

Aquaculture remains the fastest growing food producing primary industry in the world. Of the approximately 52 million tonnes of production, about 16.3 million tonnes comprises species that are fed. Marine finfish are generally strictly carnivorous and most are fed on fishmeal-based, high protein diets (>45% protein) or even directly fed “trash fish”. Current production of fishmeal is stable, and the increases in demand have been met by diverting fishmeal from other animal feeds. However, future increases in aquaculture production will require alternative protein sources.

Increasing amounts of vegetable proteins are being used but for marine carnivores, a requirement for high dietary protein, driven mainly by an inability to tolerate high dietary carbohydrate, or effectively use either carbohydrate or lipid for energy, has restricted fishmeal replacement to date. However, rendered animal protein sources, such as poultry offal meal, meat and bone meal and blood meal products are excellent protein sources with no carbohydrates and few anti-nutrients. Approximately 12.5 million tones of rendered animal meals are available globally, roughly twice as much fishmeal as is available.

Data for digestibility and utilization of rendered animal products fed to a variety of carnivorous and omnivorous aquaculture species will be presented. Data for trout, red sea bream, tilapia and mud crabs from numerous research studies will be summarized and the potential for use of rendered products discussed. The data demonstrate that rendered animal meals can be excellent protein sources for aquaculture species, including carnivorous marine finfish.

Substantial replacement of fishmeal is possible, particularly with blends of alternative protein sources based on rendered animal meals.